L9965TS datasheet(34/62 Pages) STMICROELECTRONICS

34 / 62 page

Symbol

Parameter

Test conditions

Min

Typ

Max

Unit

WAIT_RX_BEGIN

Maximum waiting time for an

answer from VIF

Tested in SCAN

µs

WAIT_RX_END

Maximum waiting time between

two successive frames received

on VIF

Tested in SCAN

6.6

8.4

µs

5.8

Communication protocol

5.8.1

Addressing procedure

At first power-up the L9965T/TS holds an address (VIF_ID_CFG.VIF_ID) equal to 0x0 and its VIF transmitter is

disabled. To communicate it is necessary to implement the addressing procedure below.

Procedure 2: L9965T/TS addressing

1. Send a SPI frame with DEV_ID = 0 to disable the configuration integrity check by writing

GENERAL_REG.CYC_CRC_DIS = 1.

The command only reaches the first device in the chain not initialized and won’t be propagated until this

device is addressed and has the VIF transmitter enabled.

2. Send SPI frames with DEV_ID = 0 to remove the configuration lock:

a. Write 0x55 in the SPECIAL_REG.SPECIAL_KEY register to enter in partial unlock

b. Write 0x33 in the SPECIAL_REG.SPECIAL_KEY register to confirm the unlock

3. Send a SPI frame with DEV_ID = 0 to program the desired VIF_ID value in the VIF_ID_CFG.VIF_ID register

4. Send a SPI frame with DEV_ID = VIF_ID_CFG.VIF_ID to enable VIF transmitter setting

GENERAL_REG.ISOH_TX_EN = 1

The steps above can be repeated for all devices in the chain that in this way are initialized one by one.

5. To enable selective broadcast (see Section 5.8.2.3), send a SPI frames with DEV_ID = VIF_ID_CFG.VIF_ID

to write the GEN_CFG1.BROADCAST_SEL<x> registers with values matching those programmed in the IC in

the chain that will be addressed by broadcast communication.

6. Send SPI commands with DEV_ID = 0 to apply the configuration lock to all devices in the chain:

a. Write 0xAA in the SPECIAL_REG.SPECIAL_KEY to apply the lock.

7. Send a SPI command with DEV_ID = 0 to enable the configuration integrity check by writing

GENERAL_REG.CYC_CRC_DIS = 0.

The device response to commands from the BMS MCU is summarized in the table below and explained in details

in following paragraphs.

Table 35. Device response according to VIF_ID

Device

VIF_ID

SPI MOSI DEV_ID

READ CMD Behavior

WRITE CMD Behavior

Discard cmd and load MISO with SPI ERROR

FRAME with WRONG_VIF_ID=1

Set COMM_ERR_SPI.SPI_VIF_ID_ERR

Perform WRITE operation and

load MISO with updated reg

content

!=0

Discard cmd and load MISO with SPI ERROR

FRAME with WRONG_VIF_ID=1

Set COMM_ERR_SPI.SPI_VIF_ID_ERR

Discard cmd and load MISO

with SPI ERROR FRAME with

WRONG_VIF_ID=1

!=0

0 (Broadcast)

Discard cmd and load MISO with SPI ERROR

FRAME with WRONG_VIF_ID=1

Set COMM_ERR_SPI.SPI_VIF_ID_ERR

Perform WRITE operation and

load MISO with updated reg

content. Propagate cmd on VIF

!=0

!=0 (matching VIF_ID)

Perform READ operation and load MISO with reg

content. No propagation on VIF

Perform WRITE operation and

load MISO with reg content.

No propagation on VIF

!=0

!=0 (non matching)

Propagate cmd on VIF transmitter and load MISO

with FIFO_RX content

Propagate cmd on VIF and load

MISO with FIFO RX content

L9965T/L9965TS

Functional description

DS14987 - Rev 1

page 34/62

L9965TS Datasheet(PDF) 34 Page - STMicroelectronics

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